arch/powerpc/kernel/prom_init_check.sh

   1 #!/bin/sh
   2 # SPDX-License-Identifier: GPL-2.0-or-later
   3 #
   4 # Copyright © 2008 IBM Corporation
   5 #
   6
   7 # This script checks prom_init.o to see what external symbols it
   8 # is using, if it finds symbols not in the whitelist it returns
   9 # an error. The point of this is to discourage people from
  10 # intentionally or accidentally adding new code to prom_init.c
  11 # which has side effects on other parts of the kernel.
  12
  13 # If you really need to reference something from prom_init.o add
  14 # it to the list below:
  15
  16 grep "^CONFIG_KASAN=y$" .config >/dev/null
  17 if [ $? -eq 0 ]
  18 then
  19         MEM_FUNCS="__memcpy __memset"
  20 else
  21         MEM_FUNCS="memcpy memset"
  22 fi
  23
  24 WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
  25 _end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
  26 __secondary_hold_acknowledge __secondary_hold_spinloop __start
  27 logo_linux_clut224 btext_prepare_BAT
  28 reloc_got2 kernstart_addr memstart_addr linux_banner _stext
  29 __prom_init_toc_start __prom_init_toc_end btext_setup_display TOC.
  30 relocate"
  31
  32 NM="$1"
  33 OBJ="$2"
  34
  35 ERROR=0
  36
  37 check_section()
  38 {
  39     file=$1
  40     section=$2
  41     size=$(objdump -h -j $section $file 2>/dev/null | awk "\$2 == \"$section\" {print \$3}")
  42     size=${size:-0}
  43     if [ $size -ne 0 ]; then
  44         ERROR=1
  45         echo "Error: Section $section not empty in prom_init.c" >&2
  46     fi
  47 }
  48
  49 for UNDEF in $($NM -u $OBJ | awk '{print $2}')
  50 do
  51         # On 64-bit nm gives us the function descriptors, which have
  52         # a leading . on the name, so strip it off here.
  53         UNDEF="${UNDEF#.}"
  54
  55         if [ $KBUILD_VERBOSE ]; then
  56                 if [ $KBUILD_VERBOSE -ne 0 ]; then
  57                         echo "Checking prom_init.o symbol '$UNDEF'"
  58                 fi
  59         fi
  60
  61         OK=0
  62         for WHITE in $WHITELIST
  63         do
  64                 if [ "$UNDEF" = "$WHITE" ]; then
  65                         OK=1
  66                         break
  67                 fi
  68         done
  69
  70         # ignore register save/restore funcitons
  71         case $UNDEF in
  72         _restgpr_*|_restgpr0_*|_rest32gpr_*)
  73                 OK=1
  74                 ;;
  75         _savegpr_*|_savegpr0_*|_save32gpr_*)
  76                 OK=1
  77                 ;;
  78         esac
  79
  80         if [ $OK -eq 0 ]; then
  81                 ERROR=1
  82                 echo "Error: External symbol '$UNDEF' referenced" \
  83                      "from prom_init.c" >&2
  84         fi
  85 done
  86
  87 check_section $OBJ .data
  88 check_section $OBJ .bss
  89 check_section $OBJ .init.data
  90
  91 exit $ERROR